Fluid pressure control device

Abstract

The safety device is disposable in the gas line connecting between a gas source under pressure and a tapping device installed in a keg. The safety device includes a valve housing carrying a spring biased, axially movable piston assembly including a valve body and an axially movable stem element. Upon an increase in gas line pressure above a predetermined pressure, the gas acts on the piston assembly to displace it as a unit in an upstream direction against the bias of the spring to seal the stem against a primary valve seat element and preclude further ingress of gas into the keg. However, should the primary valve seat element leak, due to wear or contamination, causing pressure within the system to increase, the valve body will move relative to the valve stem to vent the housing to atmosphere and to close a secondary valve seat adapted to positively prevent further fluid flow downstream of the device toward the keg.

I claim: 
     
       1. A fluid pressure control device comprising: (a) a housing having a fluid inlet and a fluid outlet and including a first internal chamber in communication with said fluid inlet, a second internal chamber in communication with said fluid outlet, and a third internal chamber in communication with atmosphere;   (b) a first valve seat carried by said housing and disposed within said first chamber;   (c) a piston assembly disposed interiorly of said housing for axial movement therewithin between first and second positions, said piston assembly comprising: (1) a piston body having an axial bore extending partially therethrough, an upper face, a lower face, and at least one fluid passageway interconnecting said axial bore and said second chamber;   (2) a second valve seat disposed within said axial bore proximate the lower end thereof;   (3) a tubular shaped stem member telescopically receivable within said axial bore of said piston body, said stem having a first end disposed in said first chamber and a second end disposed in close proximity with said second valve seat, said first end being movable into pressural engagement with said first valve seat when said piston assembly is moved from said first to said second position, and said second end being movable into pressural engagement with said second valve seat upon a predetermined degree of relative movement between said piston body and said stem; and   (4) first biasing beans for yieldably resisting relative movement between said piston body and said stem;     (d) first sealing means carried interiorly of said housing for preventing fluid flow between said second and third chambers when said piston assembly is in a first position;   (e) second sealing means disposed between said stem and said housing for preventing fluid flow between said first and third chambers; and   (f) second biasing means carried internally of said housing for yieldably resisting movement of said piston assembly from said first position to said second position when the fluid pressure within said second chamber is below a predetermined level.   
     
     
       2. A fluid pressure control device as defined in claim 1 in which said piston assembly is provided with a fluid passageway interconnecting said second chamber and said third chamber and comprises closure means for closing said fluid passageway when said piston body is in a first position relative to said stem and for opening said fluid passageway when said piston body is in a second position relative to said stem. 
     
     
       3. A fluid pressure control device as defined in claim 1 in which said housing includes upper and lower interconnected portions, in which said piston body includes upper and lower interconnected portions and in which said first sealing means comprises a diaphragm, the inner peripheral portion of which is clamped between said upper and lower portions of said piston body and the outer peripheral portion of which is clamped between said upper and lower portions of said housing. 
     
     
       4. A fluid pressure control device as defined in claim 3 in which said upper portion of said housing includes an enlarged diameter portion defining an internal shoulder and in which said second biasing means comprises an elongated coil spring the upper end of which engages said internal shoulder and the lower portion of which engages said piston body. 
     
     
       5. A fluid pressure control device as defined in claim 3 in which said stem includes a radially extending flange portion disposed proximate said second end thereof and in which said first biasing means comprises an elongated coil spring the upper end of which engages said flange portion and the lower end of which engages said second valve seat. 
     
     
       6. A fluid pressure control device comprising: (a) a housing having a fluid inlet and a fluid outlet and defining internally thereof first chamber in communication with said fluid inlet, a second chamber in communication with said fluid outlet, and a third internal chamber in communication with atmosphere;   (b) a valve element mounted within said housing said element having a first valve seat disposed within said first chamber and a fluid passageway interconnecting said fluid inlet with said first chamber;   (c) a piston assembly disposed interiorly of said housing for axial movement therewithin between first and second positions, said pistion assembly comprising: (1) an elongated generally tubular shaped stem member having a first end disposed in said first chamber in close proximity with said first valve seat and a second end normally in communication with said second chamber;   (2) a piston body having an axial bore adapted to telescopically receive said stem member, said piston body also having at least one first fluid passageway interconnecting said second chamber and said axial bore, and said piston body in cooperation with said stem member defining at least one second fluid passageway interconnecting said second chamber and said third chamber, said piston body being movable relative to said stem member from a first position to a second position;   (3) closure means for closing said second passageway when said piston body is in said first position;   (4) a second valve seat carried by said piston body in a spaced apart relationship with second end of said stem member when said piston body is in said first position; and   (5) first biasing means for yieldably resisting relative movement between said piston body and said stem member;     (d) a yieldably deformable diaphragm carried interiorly of said housing and separating said second and third chambers to prevent fluid flow therebetween when said piston assembly is in a first position;   (e) second sealing means disposed between said stem and said housing for preventing fluid flow between said first and third chambers; and   (f) second biasing means carried internally of said housing for yieldably resisting movement of said piston assembly from said first position to said second position when the fluid pressure within said second chamber is below a predetermined level.   
     
     
       7. A fluid pressure control device as defined in claim 6 in which said valve element is threadably interconnected with said housing and includes wrench engaging means for engagement by a wrench inserted into said fluid inlet portion of said housing for adjustment of the spacing between said first valve seat and said first end of said stem member. 
     
     
       8. A fluid pressure control device as defined in claim 6 in which said second passageway is opened to interconnect said second chamber with atmosphere upon movement of said piston body relative to said stem member toward said second position and in which when said piston body is moved into said second position, said second valve seat is moved into pressural engagement with said second end of said stem member.